Skip to main content
. Author manuscript; available in PMC: 2012 Sep 16.
Published in final edited form as: Expert Opin Biol Ther. 2011 Mar 7;11(5):581–593. doi: 10.1517/14712598.2011.562496

Figure 2. Retroviral vectors.

Figure 2

A. Replication-incompetent vector design. The viral gag, pol and env genes are removed and a transgene (TRGN) is inserted. Cis-acting regions including the Psi packaging region are retained. B. Self-inactivating (SIN) vector design. During vector production, vector transcripts are driven by a 5′ fusion long terminal repeat (F-LTR) promoter that contains a heterologous enhancer (grey box) fused with the viral LTR. The 3′ LTR contains a deletion in the U3 region. During reverse transcription the deleted U3 region of the 3′ LTR is copied to the 5′ LTR of the vector provirus, resulting in a provirus with flanking deleted LTRs that are essentially inactive. An internal promoter such as phosphoglycerate kinase (PGK) drives transcription.